Indicator dental floss

ABSTRACT

A floss comprising: a fiber substrate; and a uniform coating comprising a colorant, wherein the color of the coating is different than the color of the fiber substrate is disclosed. The floss is useful as an indicator floss.

FIELD OF THE INVENTION

[0001] This invention relates to a dental floss that changes color uponuse, thereby providing a visual signal or clue to indicate the need tomove to an area of the floss that has not been used. The floss comprisesa fibrous substrate to which has been applied a coating composition thatcontains a colorant. Upon use, the colorant-containing coating isdisplaced or disrupted, revealing the floss substrate, which isdifferent in color than the colorant.

BACKGROUND OF THE INVENTION

[0002] The use of dental floss is recommended by virtually all dentalhealth practitioners. Flossing and brushing are the most commontechniques for reducing bacteria in the mouth. The reduction of bacteriain the mouth is important because bacteria can cause cavities and gumdisease. Dental flossing has been shown to remove bacteria in theinterproximal as well as in the subgingival regions of the mouth.

[0003] In using dental floss, it is desirable not to use the sameportion of floss between more than one pair of teeth. One reason forthis is that floss wears during use. The floss may fray and shred,resulting in loose and broken filaments that can become stuck betweenteeth.

[0004] Another reason for not using the same portion of floss betweenmore than one pair of teeth is that the use of floss between multiplepairs of teeth can carry food particles and bacteria from one site toanother rather than out of the mouth.

[0005] Still another reason for using fresh portions of floss is fordelivery of actives such as fluoride or flavors that freshen the mouth.Repeated use of the same region of the floss obviously reduces theability of the floss to deliver desirable ingredients such as the abovementioned actives and flavors.

[0006] For the reasons mentioned above, dental professionals, such ashygienists, are taught to change floss positions when going from onepair of teeth to the next. However, most consumers do not practice thisdesirable technique. With ordinary flosses, it is sometimes impossibleto tell where the floss has been used and where it hasn't. Therefore,there is a need for a floss that provides a visual signal or clueindicating the region(s) thereof which have been previously used.

[0007] One approach to providing an indication that a portion of flosshas been used is illustrated in U.S. Pat. No. 5,941,256. The patentdiscloses a dental floss that is coated or provided withpigment-containing microcapsules on its surface. The pigment-containingmicrocapsules themselves are opaque. The opaque, pigment-containingmicrocapsules rupture during use of the floss, thereby releasing thepigment and giving a visual indication to the user that the area hasbeen used. The pigment contained within the microcapsule has a colorwhich contrasts with the color of the underlying floss substrate so thatwhen the microcapsules are ruptured, the color of the released pigmentis readily visible to the naked eye. The disadvantage of thismicrocapsule technology is that it is very expensive, thus rendering itsuse somewhat impractical from a commercial viewpoint.

[0008] Therefore, despite the disclosure of the prior art, there is acontinuing need for a dental floss that provides a visual signal or clueindicating the region(s) thereof which have been previously used.

SUMMARY OF THE INVENTION

[0009] The present invention provides a dental floss including a fibroussubstrate to which has been substantially uniformly applied a coatingcontaining a colorant, wherein the color of the coating contrasts withor is different from the color of the fibrous substrate. The colorant issubstantially uniformly present in the coating composition prior to andduring its application to the floss substrate. The colorant issubstantially uniformly present in the coating of the finished dentalfloss.

[0010] In one aspect of the present invention, there is provided adental floss comprising a fiber substrate, said fiber substrate having afirst color; said fiber substrate having a coating substantiallyuniformly applied thereto; said coating having a second color whichsubstantially completely masks said first color; whereby when said flossis used to floss the teeth, said coating is disrupted to thereby revealsaid first color, thereby providing the user with a visual indicationthat the floss has been so used.

[0011] In another aspect of the present invention, there is provided adental floss comprising a fiber substrate, said fiber substrate having afirst color; said fiber substrate having a first coating substantiallyuniformly applied thereto, said first coating being substantiallyinsoluble; and a second coating substantially uniformly applied oversaid first insoluble coating, said second coating being a solublecoating and being adapted to substantially completely mask said firstcolor, whereby when said floss is used to floss the teeth, said secondcoating is disrupted to thereby reveal an underlying color.

DETAILED DESCRIPTION OF THE INVENTION

[0012] The fibrous substrate comprising the dental floss of the presentinvention can be in the form of a monofilament or in the form of a yarncomprising a plurality of such monofilaments. A yarn comprising aplurality of monofilaments is sometimes referred to as a “multi-filamentyarn”.

[0013] A substrate in the form of a single monofilament (which issometimes referred to as a “monofilament yarn”) may be, e.g., circularor rectangular in cross section. A monofilament substrate in rectangularform typically has a width ranging from about 1.5 mm to 3 mm, athickness ranging from about 0.02 mm to about 0.06 mm, and a denierranging from about 600 to about 1800. In a specific example, arectangular monofilament substrate has a width of about 1.8 mm, athickness of about 0.05 mm, and a denier of about 940.

[0014] Substrates in the form of a multi-filament yarn are typicallygenerally circular in cross section and typically have a denier rangingfrom about 400 to about 1400. The denier of the individual fiberstypically ranges from about 1 to about 6, although other deniers may beused in some circumstances if desired.

[0015] The floss of the invention may also be made from a fibersubstrate referred to as a psuedo-monofilament yarn. Pseudo-monofilamentyarns are made by extruding bi-component fibers typically having a coreof one polymer and a sheath of a different polymer, then eitherpartially or totally melting the sheaths of the fibers to bond or fusethe fibers, resulting in a monofilament appearance and feel. One exampleof a suitable bicomponent fiber for making pseudo-monofilament yarncomprises a core of nylon 6 with a sheath of Pebax® Brandpolyether/amide copolymer. Other materials besides nylon can be used forthe core of the bicomponent fibers and other polymeric materials besidespolyether/amide copolymer may be used as the sheath material.

[0016] When the fiber substrate comprises a monofilament or amultifilament yarn, the yarns may be made of nylon 6-6, nylon 6,polypropylene, polyethylene, polyester, polytetrafluoroethylene, and thelike materials. Combinations of such materials are also acceptable aslong as they provide the floss with the strength and fray resistanceneeded in a dental floss.

[0017] The individual monofilaments comprising a multifilament yarn may,if desired, be air entangled. If the yarn is air entangled, the airentanglement nodes may be from about 1.25 cm to about 5.2 cm apart,preferably from 2 cm to 3 cm apart.

[0018] As is known in the art, the finished floss may be twisted. As ageneral rule, a finished twisted dental floss would have from about 1 toabout 6 turns per 2.54 cm, preferably from about 1 to about 2 turns per2.54 cm, and, more preferably, from about 1.2 to about 1.8 turns per2.54 cm.

[0019] A coating composition containing a colorant that is differentfrom or contrasts with the color of the floss substrate or underlyingfloss structure is applied substantially uniformly to the fibersubstrate or underlying floss structure. As the consumer uses the floss,the colorant-containing coating is disturbed or disrupted, thus exposingthe underlying substrate or floss structure which stands out due to itsdifferent or contrasting color.

[0020] In order to see the difference between a used area of floss andan unused area of floss, the floss must be substantially uniformlycoated with a coating composition containing a colorant which contrastswith or is different in color than the underlying floss material.Further, the coating must be such that use of the floss causes adisturbance or disruption in the coating, thus exposing the underlyingcolor. In one embodiment, this can be accomplished by having aninsoluble coating composition which contains an insoluble colorant andwhich is soft enough to be displaced as the floss passes between tightspaces.

[0021] In another embodiment, a soluble coating containing a solublecolorant may be applied to a fiber substrate that is different in colorthan the colorant. When this floss is used, the coating is solubilizedby saliva in the oral cavity, thus exposing the underlying flosssubstrate or structure.

[0022] Coating compositions for use in the present invention mustreliably adhere the colorant to the surface of the floss, whether thefiber substrate is a multifilament, monofilament, or psuedo-monofilamentyarn. The coating composition must have sufficient adherence to keep thecolorant-containing coating on the surface of the floss during coating,winding, shipping and unwinding of the floss.

[0023] In the case of a multifilament floss, the coating serves toadhere the filaments together to prevent fraying and shredding of thefloss during use. The coating must also be pliable at room temperaturesuch that when used, the coating is displaced or disrupted. Preferably,an insoluble coating is used on a multifilament floss to hold thefilaments together and to avoid dissolution of the coating in the salivaencountered in the oral cavity.

[0024] In one embodiment, two insoluble coatings are applied to thefiber substrate. In this embodiment, the second coating composition musthave a lower melting point than the first coating composition.Preferably, the outer coating composition contains a colorant that isdifferent in color than the underlying floss substrate carrying thefirst coating composition.

[0025] Suitable insoluble coatings include, but are not limited to,microcrystalline wax, beeswax, paraffin waxes, and low molecular weightpolyethylenes. Typically, the insoluble coatings have meltingtemperatures ranging from 25° C. to 100° C., preferably from 35° C. to80° C. The waxes may be combined with water insoluble colorants that areFD&C approved for use in the mouth. Suitable colorants include, but arenot limited to, synthetically derived colorants such as FD&C Blue #1Lake, FD&C Blue #2 Lake, FD&C Red #40 Lake, Erythrosin Lake, AmaranthLake, Ponceau 4 R Lake, Carmoisosine Lake, Carmine Lake and colorantsgenerated by converting a naturally derived dye to an aluminum orcalcium based salt. Natural colorants such as titanium dioxide and thelike may also be used.

[0026] The coating composition applied to the fiber substrate may be asoluble coating, i.e., the coating is such that it tends to dissolve ordisperse in saliva present in the oral cavity. Such soluble coatingsinclude soluble waxes or the like, which include, but are not limitedto, low molecular weight polyethylene glycols (“PEGs”), such as PEG 1000and PEG 1450. Combinations of higher molecular weight PEGs and lowermolecular weight PEGs, such as a mixture of PEG 3350 and PEG 1000 may beused. Blends of liquid PEG's with high molecular weight PEG's may alsobe used.

[0027] Soluble waxes may be used with appropriate colorants that must besubstantially uniformly dispersed within the coating. Colorants usedwith soluble waxes should be water-soluble. When formulating colorantswith PEG's it is necessary to keep the resultant average wax molecularweight low enough to maintain a soft wax and eliminate brittleness atroom temperature. When the average molecular weight of the PEG or blendsof PEG's is too high, the coating will tend to flake off the substrateduring processing and during use. Flavors, sweeteners, surfactants,abrasives, anti-tartar agents, and actives such as fluoride salts, cetylpyridinium chloride, etc. can be incorporated into the soluble coatingcompositions.

[0028] A soluble coating can be used by itself or as a second coatingover an insoluble coating. One or both coatings can contain colorants,flavors, sweeteners, abrasives, anti-tartar agents, actives, such asfluoride salts, and like additives known in the art.

[0029] Additional components can be added to coatings for variousbenefits. These include flavor systems, such as spray dried flavors,flavor enhancers, and sweeteners, such as sodium saccharin. The amountof flavor added typically ranges from 10 percent to 25 percent, based onthe total weight of the coating composition. The amount of sweetenertypically ranges from 0.1 percent to 1 percent, based on the totalweight of the coating composition.

[0030] Other components can be added to coatings to assist in cleaningthe teeth. These include actives including abrasives such as silica ordi-calcium phosphate, and anti-tartar agents such astetra-sodium-pyrophosphate. Where two coatings are used, actives areusually added in the second soluble coating to guarantee that a highpercentage of the active will be released from the floss during use.

[0031] In formulating a coating, it is desirable to limit the amount ofadditives in the coating composition below about 30% by weight. Coatinga floss substrate with a coating composition having an additive contentabove this amount may cause difficulty in achieving uniformity ofcoating and reduce the ability of the coating to adhere to the flosssurface. Coatings containing high amounts of additives may tend to flakeoff during processing and during use of the final product.

[0032] The dental floss coating may be anhydrous or hydrous. When thecoating is hydrous, the water is evaporated upon drying.

[0033] It is critical to the invention that the colorant used in anycoating system is compatible and substantially uniformly dispersed,suspended, solubilized, emulsified or dissolved in the coating. Thecolorants may be dyes, pigments, inorganic colors, Lakes, particles, orother materials that exhibit color.

[0034] For soluble coatings, the amount of colorant may range from 0.1percent to 5 percent, preferably from about 1 percent to about 3 percentby weight, based on the total weight of the coating composition.

[0035] For insoluble coatings, the amount of colorant may range fromabout 0.75 percent to about 5 percent, preferably from about 1 percentto about 3 percent by weight, based on the total weight of the coatingcomposition.

[0036] In one embodiment, the floss contains a combination of two ormore coatings of which at least the outer coating contains a colorantthat is different in color than the underlying floss structure. Use ofthe floss disturbs the coating, resulting in a visual indication thatthe area of floss has been used.

[0037] The color difference between the coating containing the colorantand the fiber substrate must be sufficiently different to serve as avisual clue or indicator to the user. If the coating on the surface ofthe floss is too thin, the amount of colorant in the coating is toolittle, or the color variation between the substrate and coating is notreadily apparent, the used area will not be readily discernable uponuse. Also, if the color of the floss varies from location to locationlongitudinally or around its periphery, a color variation resulting fromuse of the floss will not be readily apparent. For this reason, thecoating must be substantially uniform along the length of the floss aswell as around the periphery of the floss.

[0038] The coating may be applied at an add-on typically ranging fromabout 10 percent to about 60 percent, preferably from about 20 percentto about 50 percent, based on the weight of the fiber substrate. Thecoating may be applied by processes known in the art, such as dipcoating or spray coating for liquid coatings, and electrostaticdeposition for dry coatings.

[0039] In producing the floss of the invention, the colorant-containingcoating composition must be applied substantially uniformly to thesurface of the floss to insure the uniformity of the distribution ofcoating on the surface. The coating must have approximately the samethickness along the length and around its circumference of the floss. Inaddition, it is critical that the colorant be distributed substantiallyuniformly within the coating. Together, these two factors provide afinished floss of uniform color. To achieve this uniformity of color onthe floss, a coating process must used that precisely adheres a uniformcoating thickness on the surface of the floss.

[0040] In a preferred embodiment, the equipment and process for makingthe floss of the invention is capable of doing the following:

[0041] 1. Providing a coating composition in which the colorant issubstantially uniformly distributed,

[0042] 2. Maintaining the colorant in its substantially uniformdistribution in the coating composition during all subsequentoperations,

[0043] 3. Pumping the coating composition in a uniform fashion into anapplication die,

[0044] 4. Uniformly applying the coating composition to the yarn, and

[0045] 5. Keeping the coating composition substantially undisturbed onthe yarn until it is solidified intact.

[0046] The above-mentioned preferred process for making the floss of theinvention is illustrated in FIG. 1. The first step in making the flossof the invention is to substantially uniformly disperse the colorant inthe coating composition. The wax ingredient comprising this coatingcomposition is liquefied if necessary, as by heating, and added to themix tank 3. Next, colorant is added slowly to the liquefied ingredientswhile being stirred with a homogenizer 1 or through the use of a highsheer mixer 2 such as a Rotostat High Sheer Mixer Model #XPBL, made byAdmix.

[0047] Typically, a Rotosolver head blade is used in said high sheermixer and is operated at, e.g., 1700 rpm. The coating mixture is mixedin this fashion for at least 15 minutes prior to adding othercomponents.

[0048] Once the colorant has been uniformly mixed into the waxingredient, the other components of the coating composition, such asspray dried flavor, saccharin, and other desired additives, are added.After the other components are thoroughly incorporated into the coatingcomposition, the coating composition is kept uniformly mixed by a slowermoving mixer blade (not shown in FIG. 1), typically operating at about100 rpm. This speed is sufficient to keep the colorant particles insuspension, but not so fast as to stir air into the mixture.

[0049] The coating mixture is then allowed to flow into the positivedisplacement pump 4 which, when driven at a given speed, delivers aconstant amount of coating. The positive displacement pump can be a vanetype, piston pump, or similar type pump.

[0050] No matter what type of pump is used, it is necessary to keep thesolids, especially the colorant, in the mixture from settling out. Thiscan be accomplished by keeping the flow velocities of the coatingmixture sufficiently high to keep the materials in suspension or byproviding agitation of the mixture through stirring or vibration.

[0051] The fiber substrate 20 is pulled off the end of a supply spool 6,and passes over a wheel 5, which drives a pulse counter (not shown inFIG. 1). The floss substrate is pulled through the process by rewindingthe material on a take-up spool 21. The speed at which take-up spool 21is operated is controlled by controller 11. Controller 11 may be acomputer, a programmable logic controller or similar device. A signal isfed to controller 11 from the pulse counter driven by wheel 5 and thevoltage of motor 10 is also controlled to maintain a constant velocityof the yarn. Electronic controller 11 also controls the speed ofpositive displacement pump 4. Thus the speed of the floss substrate ismaintained while a constant amount of coating mixture is pumped into thecoating die 7.

[0052] The coating die 7 contains at least two rollers 22, around whichthe floss substrate has at least some wrap. Generally, the floss wrapsaround the rollers at from 90° to 720°. The rollers assist in applyingthe coating mixture to the floss substrate as well as work the mixturein between fibers (where multi-filament yarns are being utilized).Downstream of the rollers there is a slot die region 23 where thecoating mixture is smoothed onto the surface of the floss substrate. Theslot die is in the form of a V-shaped groove having a radius at itsbottom. As will be apparent to those skilled in the art, the dimensionsof the V-shaped groove will depend upon such factors as the denier andtype of fiber substrate and the amount of coating being applied thereto.

[0053] The coating composition applied to the fibrous substrate must besolidified.

[0054] Solidification can be accomplished by having a open area 8 wherethe coating cools under ambient conditions or by use of a chamber whererefrigerated or room air is blown over the floss to increase the rate ofcooling. In order to avoid undesirable discontinuities in the coating,the floss should not contact any surfaces until the coating hassolidified. Once the floss coating is cooled sufficiently to prevent anydisruption of the outer surface, it is rewound on a standard rewindmechanism 9. This mechanism holds a core on a chuck, which is rotated asan eyelet is traversed back and forth along its length. Suitabletraversing re-winders can be readily built or purchased from companiessuch as Leesona Corporation.

[0055] If it is desired to apply a second coating to the product, thismay be done by locating another coating line and cooling chamberdownstream of cooling area 8.

[0056] Several examples of the present invention are set forth below tofurther illustrate the nature of the invention and the manner ofcarrying it out. However, the invention should not be considered asbeing limited to the details thereof.

[0057] In the following Examples, the mentioned percentages are weightpercentages.

EXAMPLE 1

[0058] A natural white color multifilament nylon yarn comprising 210filaments (each filament having a denier of about 3) was coated in theabove-described manner with a coating mixture consisting ofmicrocrystalline wax (82.5%), a white colored spray dried flavor (17%)and red-colored Lake FD&C #30 (0.5%) of the kind described earlierherein. The white colored, spray dried flavor consisted of approximately20% by weight of cinnamon oil dispersed in about 80% by weight of amodified starch. The coating was applied at levels of 35, 40 and 45% byweight of the yarn. In all cases, when the finished floss was used tofloss the teeth, the portions of the colored coating which had contactedthe teeth were disrupted but no readily discernible visual clue orsignal was provided to the user. This was due to the fact that thecoating applied to the fiber substrate gave a mottled appearance to theouter surface of the coated floss. When the coating composition wasdisrupted by flossing, the underlying white color of the fiber substratewhich was thus exposed was difficult to readily distinguish from themottled appearance of the outer coating.

[0059] The aforementioned mottled appearance of the outer coatingresulted from an insufficient concentration of the red-colored lake inthe coating composition.

EXAMPLE 2

[0060] The natural white color multifilament nylon yarn used in Example1 was coated with a coating mixture consisting of microcrystalline wax(82%), red-colored spray dried flavor (17%) and red-colored Lake FD&C#30 colorant (1%). The spray dried flavor consisted of approximately 20%by weight of cinnamon oil dispersed in about 80% by weight of a modifiedstarch consisting of 98% by weight of modified starch and 2% by weightof red dye #40. The coating was applied at 35, 40 and 45% by weight ofthe multifilament yarn. In all cases, when the finished floss was usedto floss the teeth, the coating on those portions of the floss which hadcontacted the teeth was disrupted and a visual clue or signal that thefloss had been so used was provided to the user. This visual clue orsignal resulted from the fact that the red color of the floss coating,when disrupted, exposed the natural white color of the underlying yarnsubstrate. The thus exposed natural white color of the underlying yarnwas in sharp and easily noticeable contrast with the red color of theunused portions of the floss.

EXAMPLE 3

[0061] The natural white color multifilament nylon yarn used in Example1 was coated with a mixture of microcrystalline wax (81%), red coloredLake FD&C #30 (2%) and white spray dried flavor (17%) consisting ofapproximately 20% cinnamon flavor oil and 80% modified starch. Thecoating was applied at 35, 40 and 45% by weight of the yarn. In allcases, when the finished floss was used to floss the teeth, the coatingon those portions of the floss which had contacted the teeth wasdisrupted and a visual clue or signal that the floss had been so usedwas provided to the user displacement of the coating on the surfaceshowed a visible color change in the area where it was displaced.

EXAMPLE 4

[0062] The natural color multifilament nylon yarn used in Example 1 wascoated with a mixture of microcrystalline wax (86%) and white coloredspray dried flavor (14%).

[0063] The spray dried flavor consisted of 20% cinnamon flavor oil and80% modified starch. This coating was applied at 25% by weight of theyarn and the resulting yarn was white in color. To this coated,white-colored yarn was uniformly applied a second coating compositionconsisting of PEG 1450 (98%) and red dye FD&C #40 (2%). The secondcoating, which was red in color, was applied at a rate that increasedthe weight of coated yarn by an additional 15%. Displacement of thered-colored outer coating on the surface of the floss during userevealed the underlying white color, thus providing a visual clue orsignal that the floss had been used in those regions where the redcolored coating was displaced.

What is claimed is:
 1. A dental floss comprising: a fiber substrate, said fiber substrate having a first color; said fiber substrate having a coating substantially uniformly applied thereto; said coating having a second color which substantially completely masks said first color; whereby when said floss is used to floss the teeth, said coating is disrupted to thereby reveal said first color, thereby providing the user with a visual indication that the floss has been so used.
 2. A dental floss according to claim 1 wherein said fiber substrate is a monofilament.
 3. A dental floss according to claim 1 wherein said fiber substrate is a multi-filament.
 4. A dental floss according to claim 1 wherein said fiber substrate is made from a polymer selected from the group consisting of nylon 6,6, nylon 6, polypropylene, polyester, polyethylene, and polytetrafluoroethylene.
 5. A dental floss according to claim 1 wherein said coating is a soluble coating.
 6. A dental floss according to claim 5 wherein said soluble coating is selected from the group consisting of low molecular weight polyethylene glycols.
 7. A dental floss according to claim 1 wherein said coating is insoluble.
 8. A dental floss according to claim 7 wherein said insoluble coating is selected from the group consisting of microcrystalline wax, beeswax, paraffin waxes and low molecular weight polyethylenes.
 9. A dental floss according to claim 1 wherein said second color is provided by a Lake Pigment.
 10. A dental floss according to claim 9 wherein said lake is a red-colored lake.
 11. A dental floss comprising: a fiber substrate, said fiber substrate having a first color; said fiber substrate having a first coating substantially uniformly applied thereto, said first coating being substantially insoluble; and a second coating substantially uniformly applied over said first insoluble coating, said second coating being a soluble coating and being adapted to substantially completely mask said first color, whereby when said floss is used to floss the teeth, said second coating is disrupted to thereby reveal an underlying color.
 12. A dental floss according to claim 11 wherein said underlying color which is revealed is the color of said first coating.
 13. A dental floss according to claim 11 wherein said underlying color which is revealed is said first color. 